This R13 grant proposal requests support for the Fourth International Conference on Ultrasonic Biomicroscopy (UBM), a rapidly growing field of high-resolution medical imaging not yet adequately addressed in other conferences. The conference is held every 2 years by ad-hoc committees to stimulate further developments in UBM. UBM employs high-frequency (near 50 MHz) broadband transducers to provide in-vivo resolution near 30 txm. Examples of clinical applications being explored include: the anterior eye (to diagnose ocular tumors and glaucoma etiology); skin (melanomas, psoriasis, etc.); perfusion measurements; vascular-plaque vulnerability (via intravascular probes); and intrasurgical tissues, ln-vivo UBM examinations of genetically altered mice are permitting serial studies of developmental anomalies over time, without sacrificing animals. Very high frequency acoustic microscopy can examine living unstained cells with resolution at least comparable to optical microscopy. The UBM conference, the fast in the United States, will convene on September 8 - 11, 2004 at Arden House, Harriman, New York, not far from New York City. Its goals are: assess the current state-of-the-art in UBM; foster communication among diverse multi-disciplinary UBM fields; identify key problems and solutions; and, share insights with experts in other high-resolution imaging modalities. Participants include investigators with multidisciplinary expertise including: biomedical engineering, medical imaging, transducer fabrication, acoustics, and high-resolution animal and clinical applications. Experts in other high-resolution techniques will lend perspective regarding UBM's ultimate role. Students with interests in these areas will also attend. Topics will include multidisciplinary UBM areas including: high-frequency transducer fabrication; new system concepts; scattering models and acoustic phenomena at UBM frequencies; 3-D UBM imaging; mice imaging; bloodflow and plaque assays; clinical examinations (eye, skin, etc.); acoustic cell microscopy; complementary highresolution modalities (e.g., OCT, special MRI units). Thus the meeting should be of direct interest to various braches of NIH including NIBIB, NCI, NHLBI, and NEI.